One such type of bone resection is bunion deformities which are generally found on a person's foot, more specifically they are found on a person's toes. A bunion deformity or hallux abducto valgus deformity results from the big toe deviating laterally toward the patient's smallest toe. Due to the lateral movement of the big toe, the first metatarsal bone angles toward the smaller toes on the patient's foot causing the first metatarsal bone to move out of alignment. Bunions may become irritating and in some cases very painful during walking and other weight bearing activities.
The surgical procedure to fix a bunion deformity is generally a bunionectomy which removes the protruding bone and properly realigns the metatarsal bones to correct the orientation of the foot bones and joints. A number of surgical procedures are available for correcting a bunion deformity. The bunionectomy surgical procedures generally include two stages, first an exostectomy is performed by removing the bunion and then an osteotomy is performed by cutting the metatarsal bone and realigning the two portions to a normal position. Two commonly used surgical procedures are the chevron osteotomy and Reverdin osteotomy. The Reverdin osteotomy includes removal of the medial eminence or bunion and then making two transverse cuts to remove a wedge-shaped portion of bone from the articular surface of the first metatarsal head leaving the lateral cortex intact. The chevron osteotomy includes removal of the bunion and cutting the distal end of the metatarsal bones in a V-shape to enable the bone to be moved back into the correct alignment. After the metatarsal is realigned a small bone screw may be inserted across the cut bone to hold the bone portions in the desired alignment during healing. The Reverdin or chevron osteotomy may be used for mild to moderate hallux abducto valgus deformities. The Reverdin osteotomy changes the angle of the bone segments, and is generally used for more pronounced deformities, while the Chevron moves the segments, but the axes of the bones remain generally parallel. The cuts of the Reverdin osteotomy are typically made free hand without guides, thus surgeons are unable to preplan and execute the precisely angled cuts needed for a Reverdin osteotomy, resulting in Reverdin osteotomies not being performed often, and other techniques and outcomes being performed rather than risk the difficult to visualize Reverdin osteotomy. The V-shaped cuts of the Reverdin or chevron osteotomy near the metatarsal head allow the portions of the metatarsal bones to be realigned without compromising the joint.